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| Titel |
A kinetic chemistry tagging technique and its application to modelling the stable isotopic composition of atmospheric trace gases |
| VerfasserIn |
S. Gromov, P. Jöckel, R. Sander, C. A. M. Brenninkmeijer |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1991-959X
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| Digitales Dokument |
URL |
| Erschienen |
In: Geoscientific Model Development ; 3, no. 2 ; Nr. 3, no. 2 (2010-08-10), S.337-364 |
| Datensatznummer |
250000944
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| Publikation (Nr.) |
 copernicus.org/gmd-3-337-2010.pdf |
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| Zusammenfassung |
| Isotope composition, in many cases, holds unique information on the sources,
chemical modification and sinks of atmospheric trace gases. Vital to the
interpretation and use of an increasing number of isotope analyses is
appropriate modelling. However, the exact implementation of isotopic
information in chemistry-climate models is a challenge, and often studies use
simplifications which limit their applicability. Here we implement a thorough
isotopic extension in MECCA, a comprehensive kinetic chemistry sub-model. To
this end, we devise a generic tagging technique for the kinetic chemistry
mechanisms implemented as the sub-submodel MECCA-TAG. The technique is
diagnostic and numerically efficient and supports the investigation of
various aspects of kinetic chemistry schemes. We focus specifically on the
application to the modelling of stable isotopic composition. The results of
MECCA-TAG are evaluated against the reference sub-submodel
MECCA-DBL, which is implicitly full-detailed, but computationally
expensive and thus sub-optimal in practical applications. Furthermore, we
evaluate the elaborate carbon and oxygen isotopic mechanism by simulating the
multi-isotope composition of CO and other trace gases in the CAABA/MECCA
box-model. The mechanism realistically simulates the oxygen isotope
composition of key species, as well as the carbon isotope signature transfer.
The model adequately reproduces the isotope chemistry features for CO, taking
into account the limits of the modelling domain. In particular, the
mass-independently fractionated (MIF) composition of CO due to reactions of
ozone with unsaturated hydrocarbons (a source effect) versus its intrinsic
MIF enrichment induced in the removal reaction via oxidation by OH is
assessed. The simulated ozone source effect was up to +1‰ in
Δ17O(CO). The versatile modelling framework we employ (the Modular
Earth Submodel System, MESSy) opens the way for implementation of the novel
detailed isotopic chemistry treatment in the three-dimensional
atmospheric-chemistry general circulation model EMAC. We therefore also
present estimates of the computational gain obtained by the developed
optimisations. |
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